Preservation of rubber



Patented Oct. 30, 1934 1,978,444

1-,97s,444 PRESERVATION OF RUBBER Ira Williams, Woodstow and W ll m A. Douglass, Pennsgrove, N. 5., and Arthur Merrill Neal, Wilmington, Del., assignors to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application October 11, 1933, Serial No. 693,146

12 Claims; (Cl. 18-50) This invention relates tothe preservation of 2:7-di-p-phenetyl naphthalene diamine rubber and more particularly to the incorporation therein of compounds which retard that de- H H terioration. which is norrnallydue to the action H 4 00 H A of heat and oxidation. 5 2 2 5 It is well known that many materials possess the property, when incorporated in rubber, of

retarding that deteriorationwhich rubber nor mally undergoes when. exposed to the action of 1:5-dipheny1 naphthalene diamine ill heat: and oxidation. Among the earliest types of compounds employedior this purpose were p 7 the naphthalene .diamines such as LB-naphtha I 3 lene diamine, as disclosed in U. S. Patent 1,532,393.

The importance of this class of compounds is I lessened, however, by the fact that they are m relatively toxic and also becauseof their activat-v it t ing sheet on many of the; common accelerators used in practice. I i This application is a continuation in part of 26 our copending application, Serial No. 639,4 78, filed on or about October 25, 1932. i v Y 1:8-diphenyl naphthalene diamine An object of the present invention is to provide 1 e vulcanized rubber having improved age-resisting properties. A further object is to incorporate in i n rubber a new class of compounds having exceptional preserving properties which are non-toxic and in general have no effect on the rate of cure when incorporated into rubber prior to vulcanization. Otherobjects are to provide new composi- 30 tions of matter and to advance the art. Still 7 3 g; cs

other objecifs will appear i fi l-phenyl-4-p-phenetyl naphthalene diamine These ob ects may be accomplished in accordance with our invention which comprises incor- H porating into rubber, before or after vulcanizai O tiont'hereof, compounds of the type:

H H RN-AN'R' R and R represent the same :or diilerent memt i here of the group comprising alkyl, aralkyl and or more hydroxy, alkyl or alkoxy groups. The term aralkyl as employed herein isto be underhydrogen substituted by an aryl nucleus. diamine Among the compounds of this class which we H purpose arethe following: V V

50 2:7-diphenyl naphthalene diamine in which A represents a naphthalene nucleus and aryl groups. The aryl nucleus mayv contain one stood to mean an alkyl group having at least one l-phenyl-a-mOH) -phenyl naphthalene 100 have found to be particularly satisfactory for our C 3- 1 5-di-p (OH) -phenyl naphthalene diamine 1 :5-dibutyl naphthalene diamine 2 fi-diphenyl -naphthalene-diamine C H I In order to test this class of compounds the two following stocks were prepared:

Pale crepe (3) Sulfur Tetra methyl thiuram mono sulfide 1:5-di-p(OH) phenyl amido naphthalene ONOOOO Titanox is the trade name of a mixture of barium sulfate and 25% titanium dioxide. (Gardner Chemical Synonyms and Trade Names 3d Ed. 1930 p. 328) These stocks were cured to comparable states of cure at 20 lbs. steam pressure. Their ralative aging properties were determined by suspending samples in a Bierer Davis bomb at 70 C. and 300 lbs. oxygen pressure. After 7 days under these conditions stock A was completely deteriorated, whereas stock B, containing the deterioration inhibitor, was still in good condition after 17 days, when the test was discontinued.

In order to test this class of compounds still Table I Original Tensile after stock tensile aging 3050 Completely deteriorated 2015 2500 2075 2350 3150 2350 35 3025 2375 2875 2025 2900 2500 3100 2300 3225 2725 It will be seen from this table that the compounds of this class are very efiective as inhibitors of that deterioration which rubber normally undergoes due to the action of heat and oxida- F: tion. 9L

In a further test the following stocks were prepared:

T m". A B o D E Rubber 100 100 100 100 Zinc oxid 100 100 100 100 100 Sulfur 3 a 3 3 3 Stearica 1 1 1 1 1 K Lithopone 20 20 20 2O 20 We Di-o-tolyl-guanidine .75 .75 .75 .75 .75 2:6 diphenyl naphtha lene-diamine 0.1 0. 25 5 1.0

These stocks were vulcanized for 45 minutes at 40 lbs. steam pressure. Their aging properties were determined by suspending them in an oxygen bomb at 70 C. and 300 lbs. oxygen pressure further, the following stocks were prepared: It can be seen from this table that 2:6-di- A B o D E F G H I 100 100 100 100 100 100 no 20 20 20 l l 1 a 3 3 1:8-diphenyl naphthalene diamine l-phenyli-p-phenetyl naphthalene diamina. l-phenyll-p (OH)-phenyl naphthalene diamine 1 :5-d1-p(OH)-phenyl naphthalene diamine lzfi' -dibutyl naphthalene diamine These stocks were vulcanized to a comparable state of cure at 40 lbs. steam pressure. Their aging properties were determined by suspending them in an oxygen bomb at 70 C. and 300 lbs. oxygen pressure for 4.8 hours. The results of this test are given in Table I.

phenyl-naphthalene diamine is very effective as an inhibitor of that deterioration which rubber normally undergoes due to the action of heat and oxidation. It will be further noted that this effectiveness is shown to a large extent even when very low concentrations of the inhibitor are used.

The isomers and homologues of the above compounds may also be employed.

The compounds of our invention are likewise eifective when added to the rubber after vulcanization by any of the commonly applied methods of impregnation.

In the examples, We disclosed the use of one part of the deterioration inhibitor to l00'parts of the rubber. However, the proportion of deterioration inhibitor employed may be varied within rather Widelimits, depending upon the desire of the user and the nature of the rubber stock employed.

While We have disclosed compositions containing specific compounds and specific methods of preparing the same, it will be readily apparent that the specific compounds employed and the methods of employing the same may be widely varied without departing from the spirit of our invention. Accordingly, the scope of our invention is to be limited solely by the appended claims construed as broadly as is permissible in view of the prior art.

We claim:

1. The method of preserving rubber which comprises incorporating therein a compound of the type:

in which R and R represent members of the group consisting of alkyl, aralkyl and aryl groups.

2. The method of preserving rubber which comprises incorporating therein a compound of the type:

t n R-I|\I in which R and R represent similar members of the group consisting of alkyl, aralkyl and aryl groups.

3. The method of preserving rubber which comprises incorporating therein a compound of the type: v

in which R and R represent different members of the group consisting of alkyl, aralkyl and aryl groups.

4. The method of preserving rubber which comprises incorporating therein 2:6-diphenyl- 8O naphthalene-diamine.

5. Rubber having incorporated therein a compound of the type:

I NR

1'1 1 1 H in which R and R represent members of the group consisting of alkyl, aralkyl and aryl groups.

6. Rubber having incorporated therein a compound of the type:

R N t in which R and R represent similar members of the group consisting of alkyl, aralkyl and aryl groups.

'7. Rubber having incorporated therein a compound of the type:

T H RlTI in which R and R represent difierent members of the group consisting of alkyl, aralkyl and aryl groups.

8. Rubber having incorporated therein 2:6-diphenyl-naphthalene-diamine.

9. The method of preserving rubber which comprises incorporating therein 2:6 diethyl naphthalene diamine.

10. The method of preserving rubberwhich comprises incorporating therein 2-benzyl-6p(OH) phenyl naphthalene diamine. 1

11. Rubber having incorporated therein 2:6 diethyl naphthalene diamine.

12. Rubber having incorporated therein 2-benzy16-p(OH) phenyl naphthalene diamine.

IRA WILLIAMS. WILLIAM A. DOUGLASS. ARTHUR MORRILL NEAL.

CERTIFICATE OF CORRECTION.

Patent No. 1,978,444. October so, 1934.

MIRA WILLIAMS, ET AL.

it is hereby certified that error appears in the printed specification oi the above numbered patent. requiring 'correctiou es follnws: Page 2, line 45, for the syllable "rais ,readrell-gand line 63, column!) (line 6 of the tab read .75: and that the said LettersPatent should be read with these corrections therein that the same may coirform to the record 0f the case in the Patent Office.

Signed au'd sealed this 18th day of December, A D. 1934.

Leslie Frazer (Seal) Acting Commissioner oi Patents.

.2), for 57" 

